Cancer is one of the most common causes of morbidity and mortality throughout the world today. Cancer incidence is expected to increase due to increasing average life expectancy, with the onset age being lowered. The ACS (American Cancer Society)'s annual Cancer Statistics article reports that in 2007, 12 million or more new cancer cases were diagnosed worldwide, with the death toll of about 7.6 million cancer patients at a death rate of about twenty thousands per day.
Lung cancer, breast cancer and colon cancer are representative of the most deadly cancer. Particularly with regard to colon cancer, its incidence of colon cancer has been dramatically increasing in South Korea. It is the fourth leading cause of cancer-related death among men in Korea, after stomach cancer, lung cancer and liver cancer. Similar rates of cancer mortality are found for women. Most cases occur among patients in their 50s, and secondly, in the 60s. The age of the greatest incidence of colon cancer in Korea is 10 years lower than that in the Western world in countries such as the U.S.A. and the Europe. In the 30s, the high incidence frequency of colon cancer accounts for 5% - 10% of all cases. Cases in the young are uncommon unless a family history of early colon cancer is present. Factors which have an influence on carcinogenesis are, for the most part, environmental, such as the westernization of the diet, particularly excess intake of animal fats and proteins, rather than heredity. Only 5% of colon cancer cases are attributed to hereditary predisposition. According to this fact and recent reports, persons with a high risk of developing colon cancer are those who 1) have been affected by colon polyps, 2) have a family history of colon cancer, 3) suffer from ulcerative colitis for a long period of time, or 4) are attacked by intractable anal fistula.
When detected at an early stage, colon cancer can be almost completely cured by endoscopic resection or surgical operation. Further, although metastasized to the liver or the lung (distant metastasis), colon cancer may still be completely cured through surgical therapy unless found too late to be operated upon. It is, however, very difficult to detect colon cancer in asymptomatic patients since the patients with colon cancer have no subjective symptoms in the early stage. In spite of inconvenience and pain, accordingly, a periodic examination must be made to detect colon cancer at the early stage which allows the surgical operation to be applied for a cure. An occult blood test is considered to be relatively convenient colon cancer screening. However, a positive response in this test is often determined to be false positive. Likewise, all negative responses do not guarantee the absence of colon cancer. That is, it is unreasonable to use the occult blood test as an accurate diagnostic method.
Leading to the present invention, intensive and thorough research into the diagnosis of and therapeutics for colon cancer, resulted in the finding that certain genes and their expression products can be used as diagnostic markers for accurately detecting colon cancer in an early stage and as targets for the treatment of colon cancer.